 MIDAS FAQ
Q: What is MIDAS?
MIDAS (Multi-Tier Distributed Application Services) is used to build distributed applications on the Windows platform with DCOM, TCP/IP or OLE Enterprise. MIDAS provides a suite of advanced components for Delphi and C++ Builder, services, and core technologies for multi-tier application development. With MIDAS, you can build thin client applications whose business rules can be maintained on the server and automatically updated on the client. Focal points of MIDAS are:
- high server availability with fail-over safety
- disconnected database operations
- intelligent cached updates
- load balancing
- distributed datasets and transaction processing
- thin client applications
- automatic database constraint propagation
- high speed database connectivity
- reduced network traffic
Q: Why do I need MIDAS?
A: According to the Gartner Group, 40 percent of white-collar workers will be location-independent or mobile by the year 2000. (Over 30 million laptops are sold each year.) The Gartner Group also said, "The percentage of worldwide IT budgets allocated to supporting bandwidth-challenged mobile and remote users will grow from less than 5 percent in 1996 to over 30 percent by 2001, despite decreases in telecommunications costs (0.7 probability)." As today's computing infrastructure gets larger, decentralized, and more complex, IT organizations are looking for the technologies that can provide solutions today. MIDAS delivers distributed applications faster, easier, and with higher performance on bandwidth-challenged networks than any competing solution.
Q: How can I use MIDAS?
A: MIDAS (Multi-tier Distributed Application Server) is designed for quickly and easily developing and deploying multi-tier thin-client database applications. With the MIDAS development kit provided in Delphi and C++ Builder, you can deliver these applications faster than with any other tool, requiring very little coding.
For maximum development speed and flexibility, MIDAS supports server based data access, business rules, and data constraints. Data Constraints are automatically propagated from the server to the client, where they are enforced. Enforcing the constraints on the client reduces processing errors and increases overall network performance. This also means greater performance for the end-user of the application. Server-based data access requires no deployment of the Borland Database Engine on every client machine thereby reducing the maintenance costs of your applications.
MIDAS' thin client, zero-configuration deployment is perfect for mobile applications. Taking less disk space and allowing business rules to be maintained on the server increases maintenance modifications. When client applications are physically disconnected from the server, all data changes and additions are automatically tracked without having to write any code. These changes are saved locally until the client can reconnect to the server. When "briefcase mode" operations are completed, the client application simply reconnects to the server and sends all updates at once to the MIDAS server, which automatically resolves them into the master database.
MIDAS developers have the most choices in native, high-speed SQL Links for industry-standard database engines like Oracle, Microsoft SQL Server, DB2, Sybase SQL Server and InterBase. Through the power of the MIDAS data-aware components, it is even possible to change the server-side database without requiring changes to the thin client application.
Q: How do I use Microsoft Transaction Server (MTS) and MIDAS together?
A: MIDAS and MTS are complementary technologies. MTS is a transaction server which manages transactions for objects. These objects are written by Delphi and C++ developers and managed by MTS. The components may have database connections by indicating they are transactional, or they may not. If these components contain ODBC connections for Microsoft SQL Server, these connections become part of the transaction, and MTS can talk directly with the ODBC Driver. MTS developers using MIDAS gain thin client briefcase mode, automatic constraint and business rule updates, data updates, and support for database engines other than Microsoft SQL Server.
Q: What is the difference between MIDAS and Microsoft's Remote Data Services (RDS)?
A: RDS functionality was modeled after MIDAS resulting in some similarities between the two. However, MIDAS provides many features not found in RDS. RDS was designed only to be a web-based client for data access and can't be used for stand-alone applications, where as MIDAS is browser independent. RDS also dictates the use of Internet Explorer 4. MIDAS provides data constraints, data aware controls, support for heterogeneous networks, master-detail support, robust conflict resolution, and support for business rules on the middle tier, all of which can not be found in RDS. These MIDAS features allow you to be more responsive to your changing business needs. Develop robust, flexible, rapidly evolving thin client multi-tier applications with a minimum of time and code.
Q: Can Java clients be used with a MIDAS server?
A: Absolutely. Cross-platform Pure Java clients can be developed with the MIDAS Client for Java, an add-in for JBuilder 2 Client/Server or above. See http://www.inprise.com/midas/client4java.html for further information.
Q: What data sources can I use with MIDAS?
A: borland.com provides the Borland Database Engine, which includes SQL Links drivers for high-speed, native connections to SQL database engines. MIDAS dataset providers can also use VCL TDataSet descendants for a variety of data access options, including ADO, OLEDB, and ODBC.
Q: Can exceptions that occur on the server be passed to the client? For example, if the client calls a procedure on the server which performs a calculation, and a divide by zero error occurs, what will happen with regard to the exception?
A: Yes. If an exception is raised at the server, it can automatically be passed to the client that initiated the operation. The developer may choose whether or not a particular exception or class of exceptions should be handled by the server. If the client should handle an exception, the server source code can simply raise the exception and pass it on to the client. This feature can shorten processing time. It also allows business rules to be applied on the Server, centralizing maintenance and reducing maintenance costs.
Q: Can a "publish and subscribe" mechanism be used between the Server and the Client?
A: Yes. In addition to using automation methods to communicate between the server and the client, as mentioned above, an exception can be raised that will be sent to the client. This allows the client to respond to server messages without having to poll the server across the network, reducing network traffic and increasing performance of both the server and the client.
Q: Can MIDAS servers and clients developed with C++ Builder be used with Delphi? What about the reverse?
A: Absolutely. A C++ Builder developed thin-client application can receive and send data and updates to a Delphi-developed MIDAS server, and vice versa. We know our customers have multiple development groups with differing skill sets. Providing these groups the development features they need in their preferred language is a primary goal at Borland. The interoperability of C++ Builder and Delphi (and JBuilder in the future), is key to on-time and on-budget software development efforts.
Q: MIDAS has support for CORBA/IIOP, DCOM, and TCP/IP. Which one should I use?
A: It depends on your needs. TCP/IP is the simplest protocol and can be used in the most environments but it doesn't provide load balancing, fail-over, or security. Using MIDAS over CORBA or DCOM provides load balancing, fail-over, and security if needed.
Q: What is the pricing of MIDAS?
A: This depends on your deployment requirements. We have introduced new licensing options for MIDAS 2, including per-user licensing. There are licensing options, available for MIDAS. Contact your sales representative for current pricing. Volume, VAR, and business partner discounts are also available. An Unlimited MIDAS server can have multiple applications running on it and there are no licensing limits on the number of clients accessing the server. A development license for MIDAS is included with the Client/Server or Enterprise versions of Borland Delphi and Borland C++ Builder.
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